The following pics show average adult vent shots and the basic features for sexing that species:
(Click on thumbnails to view larger image)
Females on the left, Males on the right
Diplodactylus sp. and similar (Lucasium, Rynchoedura)
Male Below: note the cluster of spines at the front edge of the hemipenal bulge. Hemipenal bulges in these species can shrink in the non breeding season but the spine cluster can always be used for sexing